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    <title>Document</title>
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<script>
    function f1(){
        var tmp = 1;
        this.x = 3;
        console.log(tmp); //A
        console.log(this.x) //B
        return tmp
    }
    // var obj = new f1(); //1
    // console.log(obj.x) //2
    console.log(f1()); //3

</script>